SOUTH Australian police have launched a murder investigation after the remains of a child were found dumped beside a highway this week.

“The child was originally in the suitcase and at some point, somebody has, we believe removed the child from the suitcase”, he said. But he did say it was obvious the remains were that of a small child.

It was found by a passing motorist on Tuesday but not reported to police until yesterday.

Superintendent Des Bray said the remains themselves were found immediately behind a bush near the two-metre verge aside the Karoonda Highway bitumen.

“We have no description of the clothes he was wearing but he was carrying a dark-coloured suitcase in one hand… he was not a local”, he added in comments carried by the ABC.

“It is clear this is a suspicious death and a murder”, he said.

Others had opened the suitcase, some had even “poked around… not realising the importance of what was inside”.

Officers and volunteers on Thursday conducted an extensive search of the surrounding bush.

Police were contacted by a member of the public on Wednesday morning after the bones were found just off the highway.

The crime scene was under police guard overnight, with further forensic examination to take place on Thursday morning, along with interviews with neighbours.

Superintendent Bray said state and national missing persons databases will be checked in relation to the case.

Police said it appeared that someone had pulled the suitcase from where it had originally been dumped and placed it in full view of the road. “We’d encourage people to think about friends, acquaintances, people who live near them… and perhaps on reflection might be concerned that a child might not be around who was there previously”.